A related art inkjet head is constructed such that a piezoelectric element provided in an ink chamber is driven, and ink in the ink chamber is ejected from a corresponding nozzle hole, and includes a drive IC for driving the piezoelectric element. If the amount of operation of the drive IC increases, the amount of generated heat increases. Thus, the heat is required to be prevented from being conducted to an actuator part including the piezoelectric element and the like, and various structures for that purpose are proposed. Besides, ink supplied into the ink chamber of the actuator part and ejected from the nozzle hole may adhere to a connection part with the piezoelectric element of the actuator part, a wiring board or the like, and structures for preventing the adhesion are also proposed.
In general, the drive IC is attached in a state where the drive IC contacts the inner surface of a side wall of a frame body constituting an outer shell of the inkjet head, and the heat generated in the drive IC is radiated to the outside through the frame body side wall as a heat sink in contact with the drive IC. The actuator part to eject ink from the nozzle hole is provided at an end of the frame, and the periphery of the actuator part is covered with a mask part.
The temperature of the drive IC rises up to about 85° C. when ink is continuously ejected. If the heat is conducted to the actuator part, the viscosity of the ink is changed, or the characteristic of the actuator part is changed, and therefore, the ejection characteristic is changed. Thus, a gap is provided between the heat sink (frame body side wall) for radiating the heat of the drive IC and the mask part covering the actuator part, so that the heat of the heat sink is not conducted to the mask part and the influence of the heat is suppressed. That is, if the gap is not provided, the heat of the drive IC is conducted to the mask part and is conducted to the actuator part, and the influence of the heat is exerted on the actuator part.
However, if the gap exists between the heat sink and the mask part, it is conceivable that ink mist during use intrudes, or ink climbs up along the outer surface of the mask part and intrudes at the time of head maintenance (purge, wipe, etc.). If the ink or the like intrudes through the gap as stated above, the ink adheres to a connection part for transmitting a signal to the actuator part or a printed board, and there arises a problem such as peeling of the connection part or a failure of the board.
According to exemplary embodiments described herein, an inkjet head is provided in which ink does not intrude through a gap between a heat sink and a mask.